Hi I am using the CAT true move 3G dongle for mobile internet access.

I tried to use a 5m long USB extention cable in an attempt to put the dongle up higher for longer range

but the laptop did not recognize the device thru the cable. Am I trying to do something impossible?

Thanks

Try putting the dongle in to a Powered hub and put that at the end of the 5 metre extension.

There may be a vltage drop in the cable that is stopping the dongle from working

I experimented with a USB converter extension cable purchased from a local IT shop , and put my CAT 3G dongle high up on my roof , worked fine ,

Same USB extension as this one

and the USB dongle on the roof

I used to have 10m el cheapo USB cable connected between CAT CMDA modem and wireless router. Worked fine at the time.

But as said, using powered USB hub might improve your situation.

Btw. Should the USB hub be close to the computer/router or at the end of the long cable?

Ideally the hub should be at the dongle

USB max Length is 2–5 m (6 ft 7 in–16 ft 5 in) (by category), more than that is a miracle without a powered hub(acting as a repeater BTW)

Depends very much on the device you connect.

Did exactly the same before with a 3G dongle, using a 5m extension cable.

Worked perfectly fine using the USB ports on the back of my desktop PC (the ones directly on the mainboard), but when using the USB ports on the front of the case, I also got the "device not recognized" problem.

These 3G dongles can eat quite some power, so the powered USB hub very well might be a good solution...

Strangely enough a fair few of the Samsung galaxy range phones have the same issue, only working properly from the back USB ports.